Methods and apparatus to scan a wireless communication spectrum

ABSTRACT

Methods and apparatus are disclosed to scan a wireless communication spectrum. An example method disclosed herein includes causing a first scanner to determine, for a frequency of a wireless communication spectrum, a decoded base station identifier, causing a second scanner to determine a plurality of signal strengths at the frequency without determining a base station identifier, and determining that the base station identifier is associated with a subset of the plurality of signal strengths by comparing at least one of timestamps and locations associated with the base station identifier and the plurality of signal strengths.

FIELD OF THE DISCLOSURE

This disclosure relates generally to wireless network monitoring, and,more particularly, to scanning a wireless communication spectrum.

BACKGROUND

Frequency or channel scanners are generally used in network planning. Ascanner used in cellular communication networks, such as the GlobalSystem for Mobile Communications (GSM), can determine the signalstrength of signals transmitted on channels in the wireless networkspectrum, allowing carriers or users of the network to determine thebest locations to receive service or where better service is needed ornot needed. Scanners may generally scan all frequencies or subset offrequencies of the communication network spectrum and sample informationfrom any frequencies that are identified. Generally speaking, signalsare only detected on frequencies used by base stations in the area.

Accordingly, the scanner can sample signals on the identifiedfrequencies and decode information transmitted over the channels toobtain identifying information, such as a base station identificationcode (BSIC). A base station identification code is a unique identifierused in GSM to identify a base station. When considering the size of thespectrum or network, the number of channels being scanned directlyaffects the amount of time required to scan the network spectrum and todecode the channel information.

Typically, each cell of the cellular communication network is assigned aunique base station control channel (BCCH). Each cell is also assigned aBSIC. A BCCH is a broadcast channel used by a base station to sendinformation about the identity of the network. Depending on the poweroutput of the base station, the BCCH, BSIC pair will be unique for acell range radius.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate an example wireless communication environment ofuse for a scanning device constructed in accordance with the teachingsof this disclosure.

FIG. 2 is a block diagram of an example scanning device constructed inaccordance with the teachings of this disclosure.

FIGS. 3A-3D are graphs demonstrating example signal measurements of theexample scanning device of FIG. 2 being used in the example wirelesscommunication environment of FIG. 1 for a first channel (FIGS. 3A-3B)and a second channel (FIG. 3C-3D).

FIG. 4 is a flow chart representative of first example machine readableinstructions that may be executed to implement the example scanningdevice of FIG. 2.

FIG. 5 is a flow chart representative of second example machine readableinstructions that may be executed to implement the example scanningdevice of FIG. 2.

FIG. 6 is a flow chart representative of third example machine readableinstructions that may be executed to implement the example scanningdevice of FIG. 2.

FIGS. 7-11 are flow charts representative of example machine readableinstructions that may be executed to implement the example correlator ofthe example scanning device of FIG. 2.

FIGS. 12A-12B illustrate example data structures stored in exampledatabases of the example scanning device of FIG. 2.

FIG. 13 is a block diagram of an example processor platform that mayexecute the instructions of FIGS. 4-10 and/or 11 to implement theexample scanning device of FIG. 2.

DETAILED DESCRIPTION

When scanners are used to both measure signal strength and decodechannel information to identify a base station identification code(BSIC), the sampling rate is typically rather slow. Therefore, thelength of time to receive the signal strength measurement and decode theBSIC could be a rather lengthy period of time (e.g. up to 20 seconds).If a user is traveling at a high rate of speed over the course of thatperiod of time, the user will be unable to accurately determine thelocation corresponding to the signal strength measurement.

Removing the decoding process from the scanner allows the scanner todrastically increase its scanning rate. Although this provides a moreaccurate reading of the geographic location at which a signal strengthmeasurement occurred, the ability to identify the source of that signal(e.g. the BSIC) is lost. However, because each cell generally has aunique base station control channel (BCCH) and BSIC pair, for thoseareas where the BSIC has already been successfully decoded, the BSIC canbe correlated to signal strength measurements made within the cell,without having to decode the BSIC information when taking those signalstrength measurements.

Methods and apparatus to scan a wireless communication spectrum aredisclosed herein. Example methods disclosed include causing a firstscanner to determine for a signal detected at a first frequency adecoded base station identifier and causing a second scanner todetermine a plurality of signal strength measurements for a plurality ofsignals detected at the first frequency without determining a basestation identifier. Such example methods also include determining thatthe base station identifier is associated with a subset of the pluralityof signals by comparing at least one of timestamps and locationsassociated with the base station identifier and the plurality of signalstrength measurements.

In some examples, the wireless communication spectrum is a global systemfor mobile communications (GSM) network. In some examples, the first andsecond scanners are the same scanner having two digital signalprocessors (DSPs). In some examples, the first and second scannersoperate substantially simultaneously. In some examples the first andsecond scanners scan different frequencies of the wireless communicationspectrum at the same time. In some examples the first and secondscanners are instructed or programmed to scan multiple frequencies inthe wireless communication spectrum. In some examples, the first andsecond scanners store the BSIC and the signal strength measurements in adatabase. In some examples, the first scanner determines a plurality ofsignal strength measurements for a plurality of signals on the samefrequency. In some examples the first scanner 210 scans at a slower ratethan the second example scanner 220 because the output of the secondscanner not used to decode channel information to determine a BSIC.

In some examples, the BSIC is timestamped to record a time at which asignal is decoded and the signal strength measurement is timestamped torecord a time at which the signal strength of a signal is measured.These timestamps are used to associate the BSIC to the signal strengthmeasurements for a given frequency; thereby eliminating the need for thefirst and second scanners to operate on the same frequency at the sametime. In some examples, the first scanner takes measurements at a rateslower than the second scanner. In some examples, a geographic locationof the device where BSIC information is decoded for the frequency andwhere signal strength is measured for the frequency is detected. Thisgeographic location is used to associate the BSIC to the signal strengthmeasurement. In some examples both timestamping and determining ageographic location are used as described above to determine that a BSICdecoded based on the output of the first scanners associated with asignal strength measurement of the second scanner.

Disclosed example methods, apparatus, and/or articles of manufactureenable a scanner to scan a wireless a communications spectrum todetermine an increased number of signal measurements in a given timeperiod relative to prior art scanners while also being able to determinethe source of the signals received.

FIGS. 1A-1C illustrate an example wireless communication environment100, such as a portion of the Global System for Mobile Communications(GSM). The example environment 100 of FIGS. 1A-1C depicts four examplebase stations 102, 104, 106, 108, three example highways X, Y, Z, andfour measurement locations A, B, C, D along those roads. FIG. 1C alsoincludes a side street 150. The large diameter dashed circlessurrounding the base stations 102, 104, 106, 108 identify the areacoverage (e.g. a cell around the respective base station). The smallerdiameter circles concentric with the larger diameter circles representan area having high signal strength. Accordingly, measurement location Ais not within range of any of the base stations 102, 104, 106, 108;measurement location B is within a range of base station 108 having highsignal strength; measurement location C is within range of base stations104, 106, 108; and measurement location D is within range of basestations 102, 104.

An example scanning device as disclosed herein is used in the exampleenvironment 100 to measure the signal strengths of signals transmittedat different frequencies of the communication spectrum at the givenlocations A, B, C, D and to identify any base station(s) from which anysuch detected signals are broadcast. In some examples the signals aretransmitted in frequencies corresponding to broadcast control channels(BCCH) that are unique to each of the base stations. In such examples,base stations 102, 104, 106, 108 may be assigned BCCHs #2, #4, #6, #8,respectively.

In the illustrated examples, measurement location A is located outsidethe range of any of the base stations 102, 104, 106, 108. Therefore, anexample scanning device at location A would not detect signals on anyfrequencies (e.g., BCCHs #2, #4, #6, #8) of the wireless communicationnetwork 100, and thus would not detect any of the base stations 102,104, 106, 108 from which any of the signals are broadcast.

Measurement location B of the illustrated example is located withinrange of base station 108. Accordingly, an example scanning device atlocation B would be able to measure signal strength of a signaltransmitted at the frequency (e.g. BCCH #8) broadcast from base station108 and, with sufficient time, to decode the BSIC for base station 108.Furthermore, the close proximity of location B, shown within the smallerof the concentric circles surrounding the base station 108, in theillustrated example indicates the likelihood of a greater signalstrength from the base station 108.

Measurement location C of the illustrated example is located withinrange of base stations 104, 106, 108. Accordingly, an example scanningdevice at location C would be able to measure a signal strength ofsignals transmitted at the respective frequencies (e.g. BCCH #4, BCCH#6, and BCCH #8) by the base stations 104, 106, 108. Furthermore, withsufficient time, the example scanning device would be able to decode theBSIC for each of the base stations 104, 106, 108 to determine the sourceof the frequency or BCCH at that location.

In the illustrated example, measurement location D is located withinrange of base stations 102, 104. Therefore, the example scanning deviceat location D would be able to measure a signal strength of the signalstransmitted at the frequencies of the base stations 102, 104, forexample BCCH #2 and BCCH #4, respectively. Furthermore, with sufficienttime, the example scanning device would be able to decode the BSIC foreach of the base stations 102, 104 to determine the source of thefrequency or BCCH at that location.

In the illustrated example of FIG. 1, the four measurement locations A,B, C, D provide a user with a signal strength and BSIC to identify thesource of the signal detected at those locations. In the illustratedexample, four measurements are taken consecutively at locations A, B, C,D by a prior art scanning device traveling (e.g. within an automobile)along a side street 150. The prior art scanning device is unable to takea valuable number of signal strength measurements on side street 150 dueto the fact that the scanner must decode the BSIC information betweenmeasurements at locations A, B, C, D and the speed limit along paths XYZrequire the automobile to travel too fast for the calculations to becompleted. Specifically, if the prior art scanning device is traveling(e.g. within an automobile) on side street 150, a measurement may betaken at location B. However, the device may reach location D on route Zbefore having the processing capacity to make another signal strengthmeasurement because of the slow sampling rate of the prior art scannerdue to decoding the BSIC.

To overcome the problem, scanners that decode the BSIC for frequenciesof a wireless communication spectrum and make signal strengthmeasurements at an increased rate of speed to provide a greater numberof signal measurements are disclosed herein. FIG. 1B shows examplemeasurement locations (circles along highways Y, Z) which may beutilized by the example scanning device 200 of FIG. 2. Because of theincreased scanning rate and the fact that two scanners are utilized, thetraveling speed of the example scanning device 200 can be faster thanthe prior art as explained below with regard to FIGS. 3A-3D. Thus,rather than traveling on slower side street 150 of FIG. 1A, the examplescanner 200 travels on the faster route (X, Y, Z; a highway with ahigher speed limit) in FIG. 1B.

Additionally, FIG. 1C shows example measurement locations (circles alongside street 150) which may be utilized by the example scanning device200 of FIG. 2. In FIG. 1C, the example scanning device 200 is travelingthe same route as the prior art scanning device of FIG. 1A, however,because of the increased scanning rate and the fact that two scannersare utilized, the number of measurements along the route can bedrastically increased as explained below with regard to FIGS. 3A-3D.Thus, rather than only receiving a minimal amount of measurements, theexample scanner 200 makes drastically more (up to twenty times more)measurements, as shown in FIG. 1C, while on the same route and travelingthe same speed as the prior art scanner in FIG. 1A.

FIG. 2 illustrates example scanning device 200 that may be used in theillustrative environment of FIG. 1B. The example scanning device 200includes an example antenna 201, an example first scanner 210, anexample second scanner 220, an example correlator 230, an examplestorage device 240, an example timestamper 250, and an examplegeographic locator 260. The example scanning device 200 of FIG. 2includes an example communication bus 202 that facilitates communicationbetween the first scanner 210, the second scanner 220, the correlator230, the storage device 240, the timestamper 250, and the geographiclocator 260.

The example scanning device 200 of FIG. 2 scans frequencies of awireless communication spectrum of a wireless communication network,such as the illustrated example environment 100 of FIG. 1B, using theexample first scanner 210 and second example scanner 220. In someexamples, the first example scanner 210 scans each of the frequencies ofthe wireless communication spectrum via antenna 201 with BSIC decodingenabled, thus receiving a signal strength measurement and decodinginformation transmitted at each of the frequencies to determine the BSICfor each identified frequency. In some examples, the second examplescanner 220 scans each of the frequencies of the wireless communicationspectrum via antenna 201 with the BSIC decoding disabled, thus receivinga signal strength measurement without determining a BSIC for any of thescanned frequencies. In some examples, when the second example scanner220 scans the frequencies with BSIC decoding disabled, the sampling rateof the scans is faster (e.g. up to twenty times faster) than thesampling rate of the first example scanner 210 with BSIC decodingenabled. In some examples, if the first example scanner 210 and/or thesecond example scanner 220 do not detect a signal at a given frequencyduring a measurement or if the signal strength of the signal detected atthe given frequency is below a threshold value (e.g. −120 dBm), nulldata is stored for the corresponding frequency. Any appropriatetechniques for scanning the frequencies of the wireless communicationspectrum may be employed, such as scanning all frequencies of thewireless communication spectrum or a subset of the frequencies of thecommunication spectrum.

The first example scanner 210 and the second example scanner 220 of theillustrated example record information (e.g. signal strengthmeasurements, BCCH, and/or BSIC, etc.) detected and/or derived fromfrequencies of the wireless communication spectrum in example storagedevice 240. In some examples, the first example scanner 210 stores therecorded information in a first data structure separate from a seconddata structure in which the second example scanner 220 stores data. Thefirst and second data structures may be in the same or differentdatabases and/or in the same of different data storage device(s).Example data structures are shown in FIGS. 12A and 12B for recordinginformation collected by the first example scanner 210 and the secondexample scanner 220, respectively. The example data structures of FIGS.12A and 12B may be stored in the storage device 240.

The correlator 230 of the illustrated example accesses the recordedmeasurements from the first example scanner 210 and the second examplescanner 220 via the storage device 240. Correlator 230 determineswhether to associate BSIC information for scanned frequencies of thewireless communication spectrum from the first example scanner 210 areto scanned frequency measurements of the wireless communication spectrumfrom the second example scanner 220. The example correlator 230crosschecks the recorded frequency measurements from the first examplescanner 210 with the recorded frequency measurements of the secondexample scanner 220. In some examples, where the first example scanner210, having BSIC decoding enabled, records the BSIC for the frequencymeasurements and the second example scanner 220, having BSIC decodingdisabled, does not record the BSIC for the frequency measurements, thecorrelator 230 determines that the measurements of the second examplescanner 220 should be associated with a BSIC based on the correspondingfrequency measurements from Scanner 210. In some examples, thecorrelator writes the BSIC information to the corresponding frequencymeasurements from the second example scanner 220 to an example datastructure (see FIG. 12B) stored in the storage device 240. Accordingly,the correlator 230 of the illustrated example associates measurementscorresponding to a certain frequency (e.g. BCCH) measured in the secondexample scanner 220 to a BSIC decoded by the first example scanner 210for that frequency based on one or more characteristics (e.g. atimestamp and/or geolocation) of the measurements.

The timestamper 250 of the illustrated example records a timestamp wheneach measurement of the frequencies scanned by the first example scanner210 and the second example scanner 220 is made and stores the timestampwith the corresponding measurement in the database 240. In someexamples, the timestamper records a time stamp each time the firstexample scanner 210 and the second example scanner 220 each beginsscanning frequencies of the wireless communication spectrum. Thetimestamp is stored along with a corresponding measurement in a timefield of an example data structure (see FIGS. 12A, 12B) stored in thestorage device. In the example data structure of FIGS. 12A, 12B, anexample recorded measurement has a timestamp associated with eachmeasurements of the communication spectrum.

The example geographic locator 260 (e.g. Global Positioning System(GPS)) of the illustrated example records a physical location (e.g.latitude and longitude) where each measurement of the frequenciesscanned by the first example scanner 210 and/or the second examplescanner 220 is made. The geographic location is stored in the database240 with the corresponding measurement. In some examples, the geographiclocator 260 records a latitude and longitude each time the first examplescanner 210 and/or the second example scanner 220 each begins scanning afrequency of the wireless communication spectrum. In some examples, thegeographic locator 260 stores the latitude and longitude with acorresponding measurement in corresponding data fields of an exampledata structure (see FIGS. 12A, 12B) stored in the storage device. As aresult, the example data structures of FIGS. 12A, 12B, has one latitudeand one longitude associated with each measurement record.

In some examples, the correlator 230 of FIG. 2 uses information from thetimestamper 250 and/or the geographic locator 260 to determine whichmeasurement records of the first example scanner 210, if any, areassociated with scanner records of the second example scanner 220 storedin the storage device 240. In some examples, the correlator 230 uses atime stamp stored in the storage device 240 by the timestamper 250and/or the geographic location (e.g. latitude and longitude) stored inthe storage device 240 to determine which measurement records of thefirst example scanner 210, if any, are associated with scanner recordsof the second example scanner 220. In some examples, the correlator 230of the illustrated example receives a time stamp indicating when ameasurement record was made directly from the timestamper 250. In someexamples, the correlator 230 of the illustrated example receives ageographic location (e.g. latitude and longitude) where a measurementrecord was made directly from the geographic locator 260.

In some examples, when attempting to match records, the correlator 230of FIG. 2 references an example time window setting and/or an examplearea radius setting stored in the storage device 240 or within thecorrelator 230. The example time window setting is used to generatesubsets of respective measurement records created by the first examplescanner 210 and the second example scanner 220. In some examples, when atimestamp for a measurement record of the second example scanner 220 fora given frequency is within a time period designated by the time windowsetting of the first example scanner 210 for the same frequency, thecorrelator 230 associates a BSIC decoded from a record generated by thecorresponding measurement record of the first example scanner 210 to thecorresponding measurement records of the second example scanner 220. Forexample, if the first example scanner 210 decodes a BSIC for afrequency, such as BCCH #1, within the same time period of when thesecond example scanner 220 determined a signal strength measurement ofBCCH #1, then the measurement record of the second example scanner 200is associated with the BSIC decoded by the first example scanner 210. Insome examples, where T represents the example time window setting andT_(B) represents an example timestamp for a measurement record of thesecond example scanner 220, the example correlator 230 will reviewrecords generated by the first example scanner 210 within the timeperiod is from (T_(B)−T/2) to (T_(B)+T/2) for a match with the recordsgenerated by the second examples scanner 220. An example radius settingis used by the example correlator 230 of FIG. 2 to compare respectivegeographic locations of measurement records for the first examplescanner 210 and the second example scanner 220. In some examples, when ageographic location (e.g. latitude and longitude) for a measurementrecord of the first example scanner 210 for a given frequency is withina radius, designated by the radius setting, of the second examplescanner 220 for the same frequency, the correlator 230 associates a BSICdecoded from that frequency from the corresponding measurement record ofthe first example scanner 210 to the corresponding frequency of thecorresponding measurement records of the second example scanner 220within which the frequency was successfully sampled. For example, if thefirst example scanner 210 decodes a BSIC for a frequency, such as BCCH#1, within a distance radius of where a measurement record of the secondexample scanner 220 determined a signal strength measurement of BCCH #1,then the measurement record of the second example scanner 220 isassociated with the BSIC decoded by the first example scanner 210.

FIGS. 3A-3D are graphical representations of a first scanned frequency(BCCH #8) (shown in FIGS. 3A, 3B) and a second scanned frequency (BCCH#6) (shown in FIGS. 3C, 3D) displaying signal strength measurements forthe corresponding channels over time. FIGS. 3A, 3C are graphicalrepresentations of signal measurements of the first example scanner 210with BSIC decoding enabled. FIGS. 3B, 3D are graphical representationsof example signal measurements of the second example scanner 220 withBSIC decoding disabled. FIGS. 3A-3D include location information ofwhere signal measurements were taken corresponding to the measurementlocations of FIG. 1B.

Referring specifically to FIGS. 3A and 3B, the first example scanner 210and the second example scanner 220 sample a signal corresponding to afrequency, BCCH #8, broadcast from example base station 108 inaccordance with FIG. 1B. FIG. 3A illustrates signal strengthmeasurements 300A taken by the first example scanner 210 with BSICdecoding enabled. In some examples the first example scanner 210 samplesa signal corresponding to frequency BCCH #8 to determine signal strengthmeasurements 300A during a same time period that the second examplescanner 220 samples frequency BCCH #8 to determine signal strengthmeasurements 300B. In FIG. 3A, the second and third of signal strengthmeasurements 302, 304 are shown as being taken at locations B and C,respectively. A BSIC of base station 108 is determined by decoding BCCH#8 twice, once by decoding signal 302 and once by decoding signal 304.Because location A is outside of the range of base station 108, aminimal signal strength measurement is, if any, made by the firstexample scanner 210 as shown in FIG. 3A and/or the second examplescanner 220 as shown in FIG. 3B. Consequently the first example scanner210 cannot determine a BSIC at location A of FIG. 1B.

FIG. 3B illustrates a plurality of signal strength measurements ofsignals detected at a frequency, BCCH #8, over a period of time. In theillustrated example, the period of time (e.g. time window) is the samein FIG. 3B as the period of time in FIG. 3A. In this example, it isevident from FIGS. 3A and 3B that the sampling rate for measuring signalstrength is faster for the second example scanner 220 than for the firstexample scanner 210. In some examples, the sampling rate for the secondexample scanner 220 is faster than the first example scanner 210 becausethe first example scanner 220 has BSIC decoding enabled while the secondexample scanner 220 has BSIC decoding disabled. Cross-referencing themeasurements 300B shown in FIG. 3B with measurement locations of thesecond example scanner 220 in FIG. 1B explains the levels of the signalstrength measurements 300B for BCCH #8, which is broadcast from basestation 108 of FIG. 1B. For example, FIG. 3B shows minimal, if any,signal strength at location A, high signal strength at or aroundlocation B, and average signal strength at or around location C. FIG. 1Bshows location A being outside the range of base station 108, which isbroadcasting on frequency BCCH #8, location B being near the basestation 108, and location C being just within range of the base station108.

FIGS. 3C and 3D illustrate a second example frequency, BCCH#6, broadcastby base station 106 in accordance with FIG. 1B. The first examplescanner 210 and the second example scanner 220 sample BCCH #6 in asimilar manner as BCCH #8, described above with regard to FIGS. 3A and3B. FIG. 3C illustrates signal strength measurements 300C taken by thefirst example scanner 210 with BSIC decoding enabled. In some examples,the first example scanner 210 samples signals transmitted at frequencyBCCH #6 to determine signal strength measurements 300C during a sametime period that the second example scanner 220 samples transmitted atfrequency BCCH #6 to determine signal strength measurements 300C. InFIG. 3C, the third signal strength measurement 310 is shown as beingtaken at or around location C, and a BSIC of base station 106 isdetermined based thereon by decoding the signal detected at BCCH #6.Because locations A and B are outside of the range of base station 106,minimal signal strength measurements, if any, are made by the firstexample scanner 210 near locations A and B as shown in FIG. 3C, andconsequently the first example scanner 210 cannot determine a BSIC atlocations A and B of FIG. 1B.

FIG. 3D graphically represents a plurality of signal strengthmeasurements of a frequency, BCCH #6, over a period of time. In theillustrated example, the period of time (e.g. time window) is the samein FIG. 3D as the period of time in FIG. 3C. It is evident from FIGS. 3Cand 3D that the sampling rate for measuring the signal strength ofsignals transmitted on frequency BCCH #6 is faster for the secondexample scanner 220 than sampling rate of the first example scanner 210.In some examples, the sampling rate for the second example scanner 220is faster than the first example scanner 210 because the first examplescanner 210 has BSIC decoding enabled while the second example scanner220 has BSIC decoding disabled. Cross-referencing the measurements 300Dshown in FIG. 3D with measurement locations of the second examplescanner 220 in FIG. 1B explains the levels of the signal strengthmeasurements 300D for BCCH #6, which is broadcast from base station 106of FIG. 1B. For example, FIG. 3D shows minimal, if any, signal strengthsfor BCCH #6 at locations A and B, and average signal strength atlocation C. FIG. 1B shows locations A and B being outside the range ofbase station 106, which is broadcasting on frequency BCCH #6, location Cbeing just within range of the base station 106.

Referring specifically to FIGS. 3C and 3D, similar principles regardingthe signal strength measurements based on time and location as describedabove with regard to FIGS. 3A and 3B apply. However, FIGS. 3C and 3Dshow signal strength measurements for BCCH #6, broadcast from basestation 106 of FIG. 1B. In some examples, the signal measurement 310 ofFIG. 3C is measured by the first example scanner 210 before the signalmeasurements 300D is measured by the second example scanner 220 beforethe second of signal measurements 300B.

While an example manner of implementing the example scanning device 200has been illustrated in FIG. 2, one or more of the elements, processesand/or devices illustrated in FIG. 2 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the first example scanner 210, the second example scanner 220,the example correlator 230, the example timestamper 250, the examplegeographic locator 260 and/or, more generally, the example scanningdevice 200 of FIG. 2 may be implemented by hardware, software, firmwareand/or any combination of hardware, software and/or firmware. Thus, forexample, any of, the first example scanner 210, the second examplescanner 220, the example correlator 230, the example storage device 240,the example timestamper 250, and the example geographic locator 260and/or, more generally, the example scanning device 200 could beimplemented by one or more circuit(s), programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)),etc. When any of the apparatus claims of this patent are read to cover apurely software and/or firmware implementation, at least one of theexample first example scanner 210, the second example scanner 220, theexample correlator 230, the example storage device 240, the exampletimestamper 250, and the example geographic locator 260 are herebyexpressly defined to include a computer readable storage medium such asa memory, DVD, CD, etc. storing the software and/or firmware. Furtherstill, the example scanning device 200 of FIG. 2 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 2, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing the scanning device 200 of FIG. 2 are shown in FIGS. 4-11.In this example, the machine readable instructions comprise program(s)for execution by a processor such as the processor 1312 shown in theexample processor platform 1300 discussed below in connection with FIG.13. The program may be embodied in software stored on a tangiblecomputer readable storage medium such as a CD-ROM, a floppy disk, a harddrive, a digital versatile disk (DVD), a Blu-ray Disc™, or a memoryassociated with the processor 1312, but the entire program and/or partsthereof could alternatively be executed by a device other than theprocessor 1312 and/or embodied in firmware or hardware. Further,although the example program is described with reference to theflowcharts illustrated in FIGS. 4-11, many other methods of implementingthe example scanning device 200 of FIG. 2 may alternatively be used. Forexample, the order of execution of the blocks may be changed, and/orsome of the blocks described may be changed, eliminated, or combined.

As mentioned above, the example processes of FIGS. 4-11 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a tangible computer readable storage medium suchas a hard disk drive, a flash memory, a read-only memory (ROM), acompact disk (CD), a digital versatile disk (DVD), a Blu-ray Disc™, acache, a random-access memory (RAM)) and/or any other storage medium inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, brief instances, for temporarily buffering, and/orfor caching of the information). As used herein, the term tangiblecomputer readable storage medium is expressly defined to include anytype of computer readable storage device or disc and to excludepropagating signals. Additionally or alternatively, the exampleprocesses of FIGS. 4-11 may be implemented using coded instructions(e.g., computer readable instructions) stored on a non-transitorycomputer readable storage medium such as a hard disk drive, a flashmemory, a read-only memory, a compact disk, a digital versatile disk, acache, a random-access memory and/or any other storage medium in whichinformation is stored for any duration (e.g., for extended time periods,permanently, brief instances, for temporarily buffering, and/or forcaching of the information). As used herein, the term non-transitorycomputer readable storage medium is expressly defined to include anytype of computer readable storage device or disc and to excludepropagating signals.

Example machine readable instructions 400 that may be executed toimplement the scanning device 200 of FIG. 2 are represented by theflowchart shown in FIG. 4. The machine readable instructions 400 of FIG.4, upon execution, cause the scanning device 200 to scan a wirelesscommunication spectrum. At block 404, a list of channels of the wirelesscommunication spectrum to be scanned is determined. Any appropriatetechniques to determine the channel list may be used, such asheuristics, user input, etc.

At blocks 410 and 420, the first example scanner 210 and the secondexample scanner 220 are programmed with the determined channel list. Atblock 412, further described in FIG. 5, the first example scanner 210scans the channel list with BSIC decoding enabled. At block 422, furtherdescribed in FIG. 6, the second example scanner 220 scans the channellist with BSIC decoding disabled. In some examples, blocks 412 and 422occur at substantially the same time. At block 430, further described inFIGS. 7-11, the example correlator 230 associates a BSIC decoded by thefirst example scanner 210 with measurements sampled by the secondexample scanner 220. At block 440, the scanning device ends the scan ofthe wireless communication spectrum. Control may constantly loop throughblocks 412, 411, and/or 430 until an interrupt command is entered, suchas power off (block 440). Block 430 may be implemented in the scanningdevice 200 or at a separate data analyzing location.

FIG. 5 illustrates example machine readable instructions 412 that may beexecuted to implement block 412 of FIG. 4. The example instructions 412begin when the first example scanner 210 the first example scanner 210selects a channel from the list programmed in block 410 of FIG. 4. Atblock 530, the first example scanner 210 scans the selected frequencycorresponding to the channel (e.g. BCCH #6, BCCH #8) with BSIC decodingenabled. In the illustrated example, the first example scanner 210 scansthe selected frequency, identifies the signal being broadcast (e.g. fromany base stations 102, 104, 106, 108) if the signal has a signalstrength greater than a threshold value (e.g. −120 dBm), and samples theidentified frequency (e.g. BCCH #6, BCCH #8) to obtain and/or determinea signal strength measurement (e.g., 300A, 300C) and/or to determine aBSIC from the signal.

At block 540, the first example scanner 210 crosschecks the channel listto determine whether all channels in the list have been scanned for themeasurement record. If each of the channels from the channel list hasnot been scanned, the instructions return to block 520, and the nextchannel is selected to be scanned. If all of the channels in the listhave been scanned, the first example scanner 210 generates a measurementrecord (e.g., a new line of the data structure of FIG. 12A) to storeinformation (e.g. signal strength measurements and/or BSICs) for thescanned channels in the list (block 545). At block 550, the firstexample scanner 210 determines whether to rescan all channels in theprogram list. This example determination may be based on a success rateof the previous measurement record, user input, or any other appropriatecriteria. If the first example scanner 210 determines at block 550 thatall channels are to be rescanned, control returns to block 520 and a newrecord measurement is created. If the first example scanner 210determines at block 550 that the channels are not to be rescanned, theprogram of FIG. 5 ends.

The example machine readable instructions of FIG. 6 may be executed toimplement the block 422 of FIG. 4 to scan a channel list with BSICdecoding disabled. The example instructions 422 begin when the secondexample scanner 220 selects a channel from the list programmed in block420 of FIG. 4. At block 630, the second example scanner 220 scans aselected frequency (e.g. BCCH #6, BCCH #8) with BSIC decoding disabled.In the illustrated example, because BSIC decoding is disabled, thesecond example scanner 220 scans the selected frequency at a rate fasterthan the rate performed by the first scanner 210. In the illustratedexample, the second example scanner 220 samples any signal detected atthe identified frequency (e.g. BCCH #6, BCCH #8) to obtain and/ordetermine a signal strength measurement (e.g. 300B, 300D). The secondexample scanner 220 has BSIC decoding disabled, so it does not decodethe sampled signal to obtain a BSIC for the frequency.

At block 640, the second example scanner 220 crosschecks the channellist to determine whether all channels in the list have been scanned forthe measurement record. If each of the channels from the channel listhas not been scanned, the instructions return to block 620, and the nextchannel is selected to be scanned. If all of the channels in the listhave been scanned, the second example scanner 220 generates ameasurement record (e.g., a new line of the data structure of FIG. 12B)to store information for the scanned channels in the list (block 645).At block 650, the second example scanner 220 determines whether torescan all channels in the program list to generate another measurementrecord. This example determination may be based on a success rate of theprevious measurement record, user input, or any other appropriatecriteria. If the second example scanner 220 determines at block 650 thatall channels are to be rescanned, the second example scanner 220 returnsto block 620 and a new measurement record is created. If the secondexample scanner 220 determines at block 650 that the channels are not tobe rescanned, the program of FIG. 6 ends.

The example machine readable instructions of FIG. 7-11 may be executedto implement the correlator 230 of FIG. 2 and/or to correlate the datacollected by the first example scanner 210 with the data collected bythe second example scanner 220. At block 720 of the illustrated example,the example correlator 230 determines whether the first example scanner210 identified BSIC information for a scanned frequency (e.g., BCCH #2,BCCH #4, BCCH #6, BCCH #8). The correlator 230 of the illustratedexample may make the determination based on measurement records for thefirst example scanner 210 stored in the storage device 240 (see FIG.12A) or may directly receive BSIC information from the first examplescanner 210.

If the first example scanner 210 did not identify and/or sample BSICinformation for any frequencies scanned in the channel list, thecorrelator 230 ends the correlation 430. If the first example scanner210 identifies a BSIC for a frequency scanned in the channel list, thecorrelator 230 identifies the BCCH (block 740).

At block 750 of the illustrated example, the correlator 230 determineswhether the second example scanner 220 has identified and sampled asignal strength for the frequency corresponding to the BCCH identifiedat block 740. The correlator 230 in the illustrated example may make thedetermination based on measurement records of the second example scanner220 stored in the storage device 240 (see FIG. 12B) and/or by receivinginformation directly from the second example scanner 220. If thecorrelator 230 determines that the second example scanner 220 did notmeasure signal strength at the identified frequency in any measurementrecords at block 750 of the illustrated example, control returns toblock 730 to search the records of FIG. 12A for the next BSIC identifiedby the first example scanner 210. If the correlator does determine thatthe second example scanner 220 has measured a signal strength for theidentified frequency, then the example correlator 230 determines whetherto correlate and/or populate the identified BSIC for the frequency frommeasurement records of the first example scanner 210 (FIG. 12A) tomeasurement records (FIG. 12B) of the second example scanner for thefrequency (block 760). At block 760 of the illustrated example and asfurther described in FIGS. 8-11, the correlator 230 makes thisdetermination based on a time and/or geographic location of themeasurement records for the first example scanner 210 and the secondexample scanner 220. Control then advances to block 770.

At block 770 of the illustrated example, if the correlator 230determines that the data from the first example scanner 210 should notbe correlated to the data of the second example scanner 220, controlreturns to block 730 to search the records of FIG. 12A for the next BSICidentified in BSIC fields 1210A by the first example scanner 210. If thecorrelator does determine that the data (e.g. data in BSIC field 1210A)from the first example scanner 210 should be correlated to the data fromthe second example scanner 220, then, at block 780 of the illustratedexample, the correlator 230 populates a BSIC field 1210B of the secondscanner 220 measurement records (FIG. 12B) corresponding to recordswhere the frequency was measured by the second example scanner 220 withthe identified BSIC identified in BSIC field 1210A from the firstexample scanner 210 measurement record (see FIGS. 12A, 12B) (e.g., theBSIC for the BSIC fields 1210A of FIG. 12A is then allocated to the BSICfields 1210B of the corresponding records in FIG. 12B). Control returnsto block 730 to search the records of FIG. 12A for the next BSICidentified in BSIC fields 1210A by the first example scanner 210.

FIGS. 8-11 illustrates example machine readable instructions 800 whichmay be executed to implement block 760 of FIG. 7 to determine whether tocorrelate an identified BSIC in BSIC fields 1210A from a measurementrecord of the first example scanner 210 to measurement records of thesecond example scanner 220. At block 820 of the illustrated example, thecorrelator 230 determines a setting of the correlator 230. In someexamples, the setting of the correlator 230 can be entered by a user viainput devices 1322 of FIG. 13. In some examples the setting can beautomatically selected by the correlator 230 based on results of thescans of the first example scanner 210 and/or the second example scanner220. For example, automatic selection of using time only as thecorrelation setting may be appropriate when the correlator 230determines that the geographic locator 260 was unable to determine thegeographic location (e.g. due to an example GPS signal beinginsufficient to determine a latitude and longitude of the scanningdevice 200) for one or more measurement records of the first examplescanner 210 and/or the second example scanner 220.

At block 830 of the illustrated example, the correlator 230 selects theappropriate method to determine whether to correlate data from the firstexample scanner 210 to data from the second example scanner 220 bedetermining if the correlation is based on time only. If, at block 820of the illustrated example, the correlator 230 determined that thecorrelation setting is time only, the correlator 230, at block 840,determines whether the BSIC associated with the frequency identified ina measurement record of the first example scanner 210 with one or moremeasurement records of the second example scanner 220 for the frequencybased on timestamps and one or more time windows, as further describedin FIG. 9. If, at block 830 of the illustrated example, the correlator230 determines that the correlation setting is not to be based on timeonly, the correlator 230 then determines at block 850 if the correlationsetting is geographic location only.

If, at block 850 of the illustrated example, the correlator 230determined that the correlation is to be based on geographic locationonly, the correlator 230, at block 860, determines whether to correlatethe BSIC of the frequency identified in a measurement record (e.g. theidentified BSIC in BSIC fields 1210A of FIG. 12A) of the first examplescanner 210 with one or more measurement records of the second examplescanner 220 for the frequency based on geographic locations and an arearadius, further described in FIG. 10. If, at block 820 of theillustrated example, the correlator determined that the correlationsetting is not geographic location only, then the correlator 230, atblock 870, determines whether to correlate the BSIC associated with afrequency and identified in a measurement record (e.g. the identifiedBSIC in BSIC fields 1210A of FIG. 12A) of the first example scanner 210with one ore more measurement records of the second example scanner 220for the frequency based on time and geographic location usingtimestamps, one or more time windows, geographic locations, and an arearadius, as further described in FIG. 11. At block 880 of the illustratedexample, a result of the determination is output for use in block 780 ofFIG. 7.

The example machine readable instructions of FIG. 9 may be executed toimplement block 840 of FIG. 8 to correlate measurement record(s) of thefirst example scanner 210 to measurement record(s) of the second examplescanner 220 based only on time of occurrence. A time window (T) isdetermined for the correlation at block 920 of the illustrated example.The determination of the time window (T), at block 920 of theillustrated example, may be based on a user input via input devices 1322of FIG. 13 or may be adjusted by the correlator 230 based on anyappropriate criteria, such as geographic location, signal strengthmeasurement reliability, etc.

At block 930 of the illustrated example, the correlator 230 identifies atimestamp(s) of measurement record(s) of the first example scanner 210(see FIG. 12A) in which the frequency in question has been assigned adecoded BSIC. At block 940 of the illustrated example, the correlator230 identifies timestamp(s) of measurement record(s) of the secondexample scanner 220 where signal strength measurements were made for thecorresponding frequency.

At block 950 of the illustrated example, the correlator 230 determineswhether the timestamp(s) of the measurement record(s) of the firstexample scanner 210 and the second example scanner 220 are within theidentified time window determined in block 920. In some examples, theidentified time window (T) is centered on measurement record time(s)(T_(C)) at which signal strength measurement(s) are made by the secondexample scanner 220. Accordingly the span of the time window (T) is from(T_(C)−T/2) to (T_(C)+T/2). In the illustrated example, at block 950,when a time stamp for a measurement record of the first example scanner210 corresponding to the BSIC from the frequency in question is withinthe above span of time, the decoded BSIC from the BSIC fields 1210A iscorrelated to measurement records of the second example scanner 220 bypopulating BSIC fields 1210B with the corresponding BSIC of thefrequency in question.

Examples of the use of a time window are shown in FIGS. 3A-3D. In FIGS.3A, 3B a signal strength measurement of BCCH #8 made at T_(C8)establishes a center point (T_(C8)) of time window (T₈). From there, oneor more of the measurement records 300B within time window T₈, whichspans from (T_(C8)−T/2) to (T_(C8)+T/2), is assigned the BSIC decodedfor BCCH #8. Accordingly, another example of a time window in FIGS. 3C,3D shows that a signal strength measurement of BCCH #6 is made atT_(B6), which then establishes a center point of time window (T₆).

The example machine readable instructions 1000 of FIG. 10 may beexecuted to implement block 860 of FIG. 8 to correlate measurementrecord(s) of the first example scanner 210 to measurement record(s) ofthe second example scanner 220 geolocation data. A radius (R) isdetermined for the correlation at block 1020 of the illustrated example.The determination of the area radius (R), at block 1020 of theillustrated example, may be based on a user input via input devices 1322of FIG. 13 or may be adjusted by the correlator 230 based on anyappropriate criteria, such as geographic location, timing of measurementrecords, signal strength measurement reliability, etc.

At block 1030 of the illustrated example, the correlator 230 identifiesgeographic location(s) of where the scanning device 200 was located formeasurement record(s) of the first example scanner 210 (see FIG. 12A) inwhich the BSIC was identified for the frequency in question. At block1040 of the illustrated example, the correlator 230 identifiesgeographic location(s) of measurement record(s) of the second examplescanner 220 where signal strength measurement(s) were made for frequencyin question.

At block 1050 of the illustrated example, the correlator 230 determineswhether the geographic location(s) of the measurement record(s) of thefirst example scanner 210 and the second example scanner 220 are withinthe radius (R) determined in block 1020. In some examples, the radius(R) is measured from the center of an area at which signal strengthmeasurement(s) are made by the second example scanner 220. Accordingly,the area is a circle having a radius equal to the radius (R). In theillustrated example, at block 1050, when a geographic location for ameasurement record of the first example scanner 210 that decodes a BSICfrom a frequency is within the above area (as measured by radius R), thedecoded BSIC is correlated to measurement records of the second examplescanner 220 by populating BSIC fields 1210B with the corresponding BSICof the frequency in question.

The example machine readable instructions of FIG. 11 may be executed toimplement block 870 of FIG. 8 to correlate measurement record(s) of thefirst example scanner 210 to measurement record(s) of the second examplescanner based on time and geolocation data of the measurement records. Atime window (T) and an radius (R) are determined for the correlation atrespective blocks 1120 and 1122 of the illustrated example.

At blocks 1130, 1132 of the illustrated example, similar to respectiveblocks 930, 1030, the correlator 230 identifies a timestamp(s) andgeographic location(s) of measurement record(s) of the first examplescanner 210 (see FIG. 12A) in which the BSIC was identified for thefrequency in question. At blocks 1140, 1142 of the illustrated example,similar to respective blocks 940, 1040, the correlator 230 identifiestimestamp(s) and geographic location(s) of measurement record(s) of thesecond example scanner 220 of when and where signal strengthmeasurements were made for the frequency in question.

At block 1150 of the illustrated example, similar to blocks 950, 1050,the correlator 230 determines whether both the timestamp(s) andgeographic location(s) of the measurement record(s) of the first examplescanner 210 and the second example scanner 220 are within both the timewindow (T) and the radius (R) determined in blocks 1120, 1122. At block1150 of the illustrated example, when a timestamp and a geographiclocation for a measurement record of the first example scanner 210 thatdecodes a BSIC from a frequency is both within the above time window Tand area having a radius R, the decoded BSIC is correlated tomeasurement records of the second example scanner 220 by populating BSICfields 1210B with the corresponding BSIC of the frequency in question.

FIGS. 12A, 12B illustrate example data structures 1200A, 1200B stored inexample databases of the example scanning device of FIG. 2. FIG. 12Ashows an example data structure 1200A stored by the first examplescanner 210 having a title row identifying data fields for a recordidentifier, a date of the record, a time of the record, a geographiclatitude of the record, a geographic longitude of the record,frequencies (BCCHs) of the record, energy levels (Rxlevs), and BSICs ofthe record and three rows designating measurement records 1-3. Thecolumns of FIG. 12A in the illustrated example identify the above datafields and values for those data fields. In the illustrated example,BCCH[6] and BCCH[8] and their channel allocation values are provided asexamples from FIGS. 3A, 3C. In the illustrated example, correspondingsignal strength measurements (Rxlev[6] and Rxlev[8]) are provided aswell as corresponding base station identifiers, i.e. BSICs, (106, 108).All values are provided strictly as examples and do not reflect actualdecoded information or measure values. The example data structure 1200Aof FIG. 12A denotes BCCH[n], Rxlev[n], and BSIC[n] to indicate that anynumber of ‘n’ frequencies or channels may be included in the datastructure.

FIG. 12B shows an example data structure 1200B stored by the secondexample scanner 220, having the same title row as data structure 1200Aexcept for complete BSIC column. Because the second example scanner 220scans the frequencies of an example wireless communication spectrum withBSIC decoding disabled, the example BSIC column is not populated in thesecond example scanner 220 until the BSIC is correlated from the firstexample scanner 210. In some examples, the BSIC from data structure1200A is correlated to data structure 1200B when the correlator 230determines that a frequency (e.g., BCCH[6], BCCH[8]) has been scanned,identified, and sampled by the second example scanner 220 and a recordfrom data structure 1200A has a BSIC for the frequency decoded from thefirst example scanner 210. This correlation need not be done in thescanning device 200 but instead can be done at a collection facilitythat derives data from many scanning devices.

In the illustrated example, FIGS. 12A, 12B show that the first examplescanner 210 decoded and identified a BSIC for each of BCCH[6] andBCCH[8] in measurement records 2 and/or 3. Accordingly, FIGS. 12A, 12Bshow in the illustrated example that the BSICs (BSIC[6], BSIC[8]) forBCCH[6] and BCCH[8] respectively have been correlated from datastructure 1200A, as data structure 1200B has populated a BSIC value forBSIC[6] and BSIC[8] for all measurement records where BCCH[6] (records17-20) and BCCH[8] (records 4-15, 18-20) were scanned, identified, andsampled (e.g. measured a signal strength).

Furthermore, the example data structure provide the above informationalong with geographic location (latitude and longitude), enabling a userto determine which base station a frequency or signal is measured atthat location.

FIG. 13 is a block diagram of an example processor platform 1300 capableof executing the instructions of FIGS. 4-11 and/or to implement thescanning device of FIG. 2. The processor platform 1300 can be, forexample, a server, a personal computer, a mobile phone (e.g., a cellphone), a personal digital assistant (PDA), an Internet appliance, adedicated scanning device, or any other type of computing device.

The system 1300 of the instant example includes a processor 1312. Forexample, the processor 1312 can be implemented by one or more Intel®microprocessors from the Pentium® family, the Itanium® family or theXScale® family. Of course, other processors from other families are alsoappropriate.

The processor 1312 is in communication with a main memory including avolatile memory 1314 and a non-volatile memory 1316 via a bus 1318. Thevolatile memory 1314 may be implemented by Synchronous Dynamic RandomAccess Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUSDynamic Random Access Memory (RDRAM) and/or any other type of randomaccess memory device. The non-volatile memory 1016 may be implemented byflash memory and/or any other desired type of memory device. Access tothe main memory 1314, 1316 is typically controlled by a memorycontroller (not shown).

The processor platform 1300 also includes an interface circuit 1320. Theinterface circuit 1320 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB),and/or a PCI express interface.

One or more input devices 1322 are connected to the interface circuit1320. The input device(s) 1322 permit a user to enter data and commandsinto the processor 1312. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball,isopoint and/or a voice recognition system.

One or more output devices 1324 are also connected to the interfacecircuit 1320. The output devices 1024 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT), a printer and/or speakers). The interface circuit 1320,thus, typically includes a graphics driver card.

The interface circuit 1320 also includes a communication device (e.g.,antenna 201, the first example scanner 210, the second example scanner220) such as a modem or network interface card to facilitate exchange ofdata with external computers via a network 1326 (e.g., an Ethernetconnection, a digital subscriber line (DSL), a telephone line, coaxialcable, a cellular telephone system, etc.).

The processor platform 1300 also includes one or more mass storagedevices 1328 for storing software and data. Examples of such massstorage devices 1328 include floppy disk drives, hard drive disks,compact disk drives and digital versatile disk (DVD) drives. The massstorage device 1328 may implement the local storage device 240.

The coded instructions of FIGS. 4-11 and data structure of FIGS. 12A,12B may be stored in the mass storage device 1328, in the volatilememory 1314, in the non-volatile memory 1316, and/or on a removablestorage medium such as a CD or DVD

From the foregoing, it will appreciate that above disclosed methods,apparatus and/or articles of manufacture allow for a wirelesscommunication scanner to identify base stations at a higher rate ofspeed to thereby generate a secure map of a wireless communicationsystem, enabling a user to identify a source of a signal while alsobeing able efficiently scan for several signal strength measurements ofthe signal.

Although certain example methods, apparatus and articles of manufacturehave been described herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. A method comprising: detecting with a firstscanner scanning at a first rate a base station identifier for afrequency of a wireless communication spectrum; detecting with a secondscanner scanning at a second rate, different from the first rate, aplurality of signal strengths of signals at the frequency withoutdetermining a base station identifier; and determining that the basestation identifier is associated with a subset of the plurality ofsignal strengths by comparing at least one of times and physicallocations at which the base station identifier and the plurality ofsignal strengths were detected.
 2. A method as defined in claim 1,wherein the first scanner and the second scanner are located in ascanner housing and implemented by first and second digital signalprocessors, respectively.
 3. A method as defined in claim 1, whereinfirst and second scanners is operate substantially simultaneously.
 4. Amethod as defined in claim 1, wherein the first frequency corresponds toa channel of the wireless communication spectrum and the wirelesscommunication spectrum is a global system for mobile communication(GSM).
 5. A method as defined in claim 1, further comprisingtimestamping the base station identifier and the plurality of signalstrengths, wherein determining that the base station identifier isassociated with the subset of the plurality of signal strengthscomprises determining a first timestamp associated with the base stationidentifier is within a time period of a second timestamp associated withone of the plurality of signal strengths in the subset.
 6. A method asdefined in claim 1, further comprising determining a geolocation of thefirst scanner when the first scanner determines the base stationidentifier and a plurality of geolocations of the second scanner whenthe second scanner determines corresponding ones of the plurality ofsignal strengths, wherein determining that the base station identifieris associated with the subset of the plurality of signal strengthscomprises determining a first geolocation associated with the basestation identifier is within an radius of corresponding ones of theplurality of geolocations.
 7. A method as defined in claim 1, furthercomprising timestamping the base station identifier and the plurality ofsignal strengths; and determining a geolocation of the first scannerwhen the first scanner determines the base station identifier and aplurality of geolocations of the second scanner when the second scannerdetermines corresponding ones of the plurality of signal strengths,wherein determining that the base station identifier is associated withthe subset of the plurality of signal strengths comprises determining afirst timestamp associated with the base station identifier is within atime period of a second timestamp associated with one of the pluralityof signal strengths in the subset, and wherein determining the basestation identifier is associated with the subset of the plurality ofsignal strengths comprises determining a first geolocation associatedwith the base station identifier is within an radius of correspondingones of the plurality of geolocations.
 8. A method as defined in claim1, further comprising, detecting with the first scanner, determines asecond plurality of signal strengths for the frequency.
 9. A method asdefined in claim 1, wherein the second rate is faster than the firstrate.
 10. An apparatus comprising: a first scanner to scan a frequencyof a wireless communication spectrum at a first rate to identify a basestation identifier; a second scanner to scan the frequency at a secondrate different from the first rate to determine a plurality of signalstrengths; and a correlator to determine that the base stationidentifier is associated with a subset of the plurality of signalstrengths by comparing at least one of timestamps and physical locationsof the first and second scanners when the base station identifier andthe plurality of signal strengths were detected.
 11. An apparatus asdefined in claim 10, wherein the first scanner and the second scannerare located in a scanner housing an implemented by a first and seconddigital signal processor, respectively.
 12. An apparatus as defined inclaim 10, wherein the first and second scanners operate substantiallysimultaneously.
 13. An apparatus as defined in claim 10, wherein thefirst frequency corresponds to a channel of the wireless communicationspectrum and the wireless communication spectrum is a global system formobile communication (GSM).
 14. An apparatus as defined in claim 10,further comprising a timestamper to timestamp the base stationidentifier and the plurality of signal strengths, wherein the correlatordetermines that the base station identifier is associated with thesubset of the plurality of signal strengths by determining a firsttimestamp associated with the base station identifier is within a timeperiod of a second timestamp associated with one of the plurality ofsignal strengths in the subset.
 15. A apparatus as defined in claim 10,further comprising a geolocator to determine a geolocation of the firstscanner when the first scanner determines the base station identifierand a plurality of geolocations of the second scanner when the secondscanner determines corresponding ones of the plurality of signalstrengths, wherein the correlator determines that the base stationidentifier is associated with the subset of the plurality of signalstrengths by determining a first geolocation associated with the basestation identifier is within an radius of corresponding ones of theplurality of geolocations.
 16. An apparatus as defined in claim 10,further comprising a timestamper to timestamp the base stationidentifier and the plurality of signal strengths; and a geolocator todetermine a geolocation of the first scanner when the first scannerdetermines the base station identifier and a plurality of geolocationsof the second scanner when the second scanner determines correspondingones of the plurality of signal strengths, wherein the correlatordetermines that the base station identifier is associated with thesubset of the plurality of signal strengths by determining a firsttimestamp associated with the base station identifier is within a timeperiod of a second timestamp associated with one of the plurality ofsignal strengths in the subset, and wherein the correlator determinesthe base station identifier is associated with the subset of theplurality of signal strengths by determining a first geolocationassociated with the base station identifier is within an radius ofcorresponding ones of the plurality of geolocations.
 17. An apparatus asdefined in claim 10, wherein the first scanner detects a secondplurality of signal strengths for the frequency.
 18. An apparatus asdefined in claim 10, wherein the second rate is faster than the firstrate.
 19. A machine readable storage medium comprises instructionswhich, when executed, cause a machine to at least: cause a first scannerscanning at a first rate to detect a base station identifier for afrequency of a wireless communication spectrum; cause a second scannerscanning at a second rate, different from the first rate, a plurality ofsignal strengths of signals at the frequency without determining a basestation identifier; and determine that the base station identifier isassociated with a subset of the plurality of signal strengths bycomparing at least one of times and physical locations at which the basestation identifier and the plurality of signal strengths were detected.20. A storage medium according to claim 19, wherein the first scannerand the second scanner are located in a scanner housing and implementedby first and second digital signal processors, respectively.
 21. Astorage medium according to claim 19, wherein first and second scannersis operate substantially simultaneously.
 22. A storage medium accordingto claim 19, wherein the first frequency corresponds to a channel of thewireless communication spectrum and the wireless communication spectrumis a global system for mobile communication (GSM).
 23. A storage mediumaccording to claim 19, wherein the instructions cause the machine totimestamp the base station identifier and the plurality of signalstrengths, wherein the machine determines that the base stationidentifier is associated with the subset of the plurality of signalstrengths by determining a first timestamp associated with the basestation identifier is within a time period of a second timestampassociated with one of the plurality of signal strengths in the subset.24. A storage medium according to claim 19, wherein the instructionscause the machine to determine a geolocation of the first scanner whenthe first scanner determines the base station identifier and a pluralityof geolocations of the second scanner when the second scanner determinescorresponding ones of the plurality of signal strengths, wherein themachine determines that the base station identifier is associated withthe subset of the plurality of signal strengths by determining a firstgeolocation associated with the base station identifier is within anradius of corresponding ones of the plurality of geolocations.
 25. Astorage medium according to claim 19, wherein the instructions cause themachine to timestamp the base station identifier and the plurality ofsignal strengths; and determine a geolocation of the first scanner whenthe first scanner determines the base station identifier and a pluralityof geolocations of the second scanner when the second scanner determinescorresponding ones of the plurality of signal strengths, wherein themachine determines that the base station identifier is associated withthe subset of the plurality of signal strengths by determining a firsttimestamp associated with the base station identifier is within a timeperiod of a second timestamp associated with one of the plurality ofsignal strengths in the subset, and wherein the machines determines thebase station identifier is associated with the subset of the pluralityof signal strengths by determining a first geolocation associated withthe base station identifier is within an radius of corresponding ones ofthe plurality of geolocations.
 26. A storage medium according to claim19, wherein the first scanner detects a second plurality of signalstrengths for the frequency.
 27. A storage medium according to claim 19,wherein the second rate is faster than the first rate.